Film molding apparatus

ABSTRACT

A film molding apparatus wherein a film is immersed in a vessel of a film supply unit, the film containing at least 50 weight % swelling agent relative to a polymer constituting the film, and the vessel being filled with soaking liquid which acts so as not to destroy a swelling condition of the film, and a film piece corresponding to one molded product is supplied from the film supply unit to a mold press.

This is a Divisional application of Ser. No. 07/745,262, filed Aug. 14,1991, and now U.S. Pat. No. 5,273,705.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a film molding apparatus and method,and more particularly to a film molding apparatus and method capable ofmolding a para orientation type aramid film at deep drawing.

The term "para orientation type aramid" herein used throughout thespecification means a polymer of a repetition structure wherein a paraposition or equivalent position of an aromatic ring is replaced with anamido radical.

2. Description of the Related Art

The following three methods are known for deforming a thermoplastic filmwith metal dies and thermally setting it. The first method is a vacuummolding method. With the second method, a film is first clamped withheated metal dies and thereafter it is molded by cooling the metal dies.With the third method, a film is first heated and thereafter it isclamped and molded with low temperature metal dies.

The first vacuum molding method will be described with reference to FIG.13.

As shown in FIG. 13(A), a film pulled out of a roll is clamped by aclamper and heated near an oven.

After the film is heated and softened, the clamper goes down to make thefilm in contact with a metal die, as shown in FIG. 13(B).

Next, as shown in FIG. 13(C), air is sucked via holes extending from thesurface to the back of the metal die so that the film is cooled by themetal die. During the cooling operation, the oven is retracted so as notto heat the film.

After the film takes a strength retaining the shape of the metal die,the film or metal die is moved to detach the film from the metal die.

Referring to FIG. 14, there will be described the second method ofclamping a film with heated metal dies and thereafter cooling the metaldies to mold the film.

As shown in FIG. 14(A), a film is pulled out of a roll and transportedbetween metal dies. The upper and lower metal dies are pressed againstheater blocks to heat the metal dies.

As shown in FIG. 14(B), the heated upper and lower metal dies go down toclamp and mold the film. Thereafter, nozzles are disposed at the back ofthe metal dies to cool beth the metal dies and film with air. As shownin FIG. 14(C), after the film takes a strength retaining the shape ofthe metal dies, the metal dies are moved to detach the film therefrom.

Referring to FIG. 15, there will be described the third method ofheating a film and thereafter clamping the film with low temperaturemetal dies to mold the film. As shown in FIG. 15(A), an apparatus forthis method has heating and pressing sections juxtaposed each other. Afilm pulled out of a roll is clamped with heating metal dies at theheating section so that it is heated and softened.

As shown in FIG. 15(B), the softened film is transported to the nextpressing section and clamped and molded with metal dies so that the filmis cooled and takes a strength retaining the shape of the metal dies.

Next, the metal dies are moved to detach the film therefrom. The film isthen transported to pick up the molded portion and heat the next filmportion to be molded.

The above conventional molding methods are suitable for use in molding athermoplastic film having a low softening point and being likely to havea stable shape after cooling.

However, a para orientation type aramid has a very high glass transitionpoint and softening point. Therefore, the above-described conventionalmethods cannot mold such a film at deep drawing.

The first vacuum method in particular cannot such an aramid film towarda metal die if the film is not softened sufficiently, thereby disablingto mold the film.

The second and third methods can mold such a film only at shallowdrawing. If such a film is molded at deep drawing, it may sometimes bebroken during pressing, or it may sometimes change with time its shapebecause of a residual stress at the time of molding.

With the second method in particular, the metal dies are not heatedduring pressing so that the temperature control during pressing isdifficult. With the third method, the upstream and downstream of apressed portion of the film may be deformed, resulting in a lowmanufacturing yield.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above problems. It isan object of the present invention to provide a film molding apparatusand method capable of molding an aramid film into a shape of high degreeof freedom while retaining a good yield.

According to the present invention, a para orientation type aramid filmis immersed in a vessel of a film supply section after washing outsolvent at the manufacturing process and without drying, the film beingmaintained so as to contain at least 50 weight % swelling agent relativeto a polymer constituting the film. Soaking liquid is filled within thevessel so as not to destroy such a swelling condition of the film. Inthis condition, the film is cut into film pieces each corresponding toone molding product, and sequentially supplied to a mold press. Thismold press clamps and molds a film piece with metal dies. Thereafter,heater blocks are pressed against the metal dies to heat the metal diesso that the film piece is maintained at a predetermined temperature andthermally set. Next, cooling blocks are pressed against the metal diesto cool the metal dies and hence the film piece. Then, the film piecehaving an increased strength is detached from the metal dies.

As the para orientation type aramid, a polyphenylene terephthalate amido(hereinafter called PPTA) is most preferable. Depending upon applicationfields, a copolymer may be used, for example, m-phenylene, 4,4-diphenylene, 1, 4-naphthalene, 1, 5-naphthalene, 2, 6-naphthalene, 4,4-diphenylene, 3, 4-diphenylene ethylene, or a substitutional group ofthese copolymers replaced with halogen, alkyl, nitro and the like. Apolybensamido may also be used.

If the polymerization degree of a para orientation type aramid is toolow, a film sheet having excellent mechanical characteristics cannot beobtained. Preferably, a polymerization degree is selected which providesa logarithmic viscosity coefficient η inh 3.5 or higher, or morepreferably 4.5 or higher. The logarithmic viscosity coefficient is avalue measured at 30° C. with a polymer of 0.5 g dissolved into highconcentration sulfuric acid 100 ml.

As the swelling agent for maintaining a para orientation type aramid,there are, for example, water, dimethyl sulfoxide (DMSO), methanol,alkali aqueous solution, metal base aqueous solution, a mixture thereof,and the like.

According to the present invention, a para orientation type aramid filmcontains swelling agent and is maintained in a gel state at the time ofpressing. Therefore, the film can be easily molded by pressing withmetal dies. The film is maintained at a predetermined temperature for apredetermined time period while being pressed with the metal dies.Therefore, it is possible to obtain a molded product thermally set andhaving a stable dimension.

In general, a para orientation type aramid is difficult to be swelledonce it is dried and crystallized. According to the present invention, apara orientation type aramid is supplied to a mold press without dryingit so that it can be easily molded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing the overall layout of a filmmolding apparatus according to an embodiment of the present invention;

FIG. 2 is a cross section showing the main part of a material supplysection of the embodiment shown in FIG. 1;

FIG. 3 is a partial perspective view of the material supply section;

FIG. 4 is a cross section showing the outline of the material supplysection;

FIG. 5(A) and 5(B) are cross sections showing a film reception unit ofthe material supply section;

FIG. 6 is a cross section showing the main part of a mold press of thefilm molding apparatus of the embodiment shown in FIG. 1;

FIG. 7(A) is a partial cross section of the mold press;

FIG. 7(B) is a perspective view showing the upper portion of a coolingblock of the mold press;

FIG. 7(C) is a plan view of the cooling block of the mold press;

FIG. 7(D) is a cross section of the cooling block of the mold press;

FIG. 8(A) is a plan view of a die setting plate of the mold press;

FIG. 8(B) is a cross section of a die setting plate of the mold press:

FIG. 9 is a perspective view showing the upper portion of the diesetting plate of the mold press;

FIG. 10 is a cross section of a die of the mold press;

FIG. 11 is a cross section showing a modification of the die of the moldpress;

FIG. 12 is a cross section showing a speaker diaphragm molded by usingthe embodiment apparatus;

FIGS. 13(A), (B) and (C) are cross sections illustrating a conventionaltechnique;

FIGS. 14(A), (B) and (C) are cross sections illustrating anotherconventional technique; and

FIGS. 15(A), (B) and (C) are cross sections illustrating still anotherconventional technique.

DETAILED DESCRIPTION OF THE EMBODIMENT

A preferred embodiment of the present invention will be described withreference to the accompanying drawings. This embodiment is intended tobe used for manufacturing a speaker diaphragm integrally formed with adiaphragm unit, voice coil bobbin unit, and suspension unit, by using aPPTA film. An excellent performance speaker diaphragm can be obtainedbecause of high rigidity and high heat resistance of PPTA and because ofnon-use of adhesive agent.

FIG. 1 shows the overall layout of the film molding apparatus accordingto the embodiment of the present invention.

As shown in FIG. 1, the apparatus is constructed of a material supplysection 101 for supplying a PPTA film, an X, Y orthogonal robot 102 fortransporting material and intermediate products, five mold presses,103-1, . . . , 103-5, two punching press sections 104-1 and 104-2, and acontrol 105 box for controlling these elements.

The X, Y orthogonal robot has a film pickup arm 106 and a molded productpickup arm 107. The film pickup arm is used to pickup film pieces fromthe material supply section, and supply them to one of the mold presses.The molded product pickup arm is used to pick up a molded film piecefrom the mold press, and supply it to one of the punching presssections. Both the arms are moved up and down and rotated by lifts androtary actuators 108. The arms are moved in the X-Y direction togetherwith the rotary actuators so that a film piece sucked with a suction pad109 mounted at each arm end can be transported.

FIG. 2 is a cross section of the material supply section.

In FIG. 2, reference numeral 1 represents a water vessel in which waterserving as swelling agent is filled.

A molding material immersed in the water vessel 1 is a PPTA film 3 of agel state.

This film 3 was made in the following manner. PPTA having η inh 5.2 wasdissolved within 99.5% high concentration sulfuric acid to obtain 12%concentration. There was obtained at 65° C. a dope of 8200 poises havingoptical anomaly. After deairing and filtering, the dope was caused todrain via a die having a slit of 0.30 mm×300 mm onto a belt made oftantalum. Air at abut 100° C. and having a relative humidity of abut 30%was blown to the flowing dope to change it into a transparent dopehaving an optical isotropy. The dope was then introduced into lowconcentration sulfuric acid to coagulate it.

The coagulated film sheet was peeled off from the belt, and sequentiallywashed by using water at a room temperature, 0.5% sodium hydrosulfiteaqueous solution, and water at about 30° C. to 40° C., in this orderrecited. The obtained film sheet was a gel film having a thickness ofabut 250μ, a tensile strength of about 100% at a room temperature, and ahigh moisture content.

The film was cut with a slitter and wound abut a bobbin. In thiscondition, the film was immersed within the water vessel 1.

As shown in FIG. 3, the bobbin 2 about which the film was wound isrotatably supported by two sets of three rollers 4 mounted at the rightand left sides of the water vessel.

The gel film 3 is guided by guide rollers 5, becomes in contact with apad 6, and pulled out by a pressure roller 8 and a feed roller 7.

The feed roller 7 is intermittently driven by a motor 9 to feed by apredetermined length. The fed film is cut by a rotary blade 10 driven inthe vertical direction as viewed at the drawing surface and by a fixedblade 11. The cut film falls down to a film receptor 12.

Water on the surface of the film is wiped out by the pad 6 so that thewater contents become uniform over the surface, while wiping out thewater contents to the extent that cut film sheets do not attachtogether.

In order not to dry the film pulled out of the water vessel and fallenon the film receptor 12, the upper portion of the region from the vessel1 to the film receptor 12 is provided with a cover 13 as shown in FIG.4. A humidifier 14 is provided to raise the air humidity of a spaceunder the cover 13.

FIG. 5 illustrates how a film piece on the film receptor is picked up bythe suction pad of the robot. FIG. 5(A) illustrates a normal state.

FIG. 5(B) illustrates an abnormal operating state of the suction padbecause the film piece was dried and curled. This state results fromnon-use of means such as the cover 12 for preventing water on the filmsurface being evaporated.

If there is not provided the means for preventing water on the filmsurface from being evaporated, it becomes difficult to correctly supplya film piece to the mold press. Furthermore, the gel state of the filmis destroyed, resulting in the difficulty of the molding operation bythe mold press.

The mold press section is constructed by five mold presses one of whichis shown in FIG. 6.

The mold press is constructed of molding die raising/loweringmechanisms, heater blocks, cooling blocks, block sliding mechanisms,block raising/lowering mechanisms, and poles and base plates forsupporting these elements.

The molding die lifting mechanism is driven by air cylinders 15.

Poles 17 are mounted upright on a main base 18. A cylinder mountingplate 16 is fixed to the ends of the poles 17.

The air cylinder 15 is fixedly mounted on the cylinder mounting plate16. At the end of a cylinder rod 15a of the air cylinder 15, a base 19is mounted slidable with respect to the poles 17.

The base 20 is mounted with an air cylinder 19 for raising and loweringa die, the heater block 27, and the cooling block 28.

In order to control the die raising/lowering speed at two steps, thecylinder rod 15a is formed stepwise. A cylinder plate 15b is formed witha stepwise hole corresponding to the cylinder rod 15a, with an aircushion chamber being formed. Air in the air cushion chamber is expelledoutward via a needle valve.

The heater blocks 27 and cooling blocks 18 are mounted under and abovethe dies, the blocks under a die being shown in FIG. 7(A).

The block raising/lowering mechanisms and block sliding mechanism undera die will be described with reference to FIG. 7(A).

A base 21 is slidably mounted on the poles 17. The base 21 is coupled tothe end of a cylinder rod 20a of the air cylinder 20 which is fixed tothe main base, so that the base 21 is moved up and down by the aircylinder 20. The upper base 21 is driven, however, by the air cylinder20 mounted on the base 19 as described previously.

A slide rail 22 with a groove 22a is fixed to the base 21. The groove22a engages with slide plates 23 which are coupled to a rod 23b.

One of the slide plates 23 is coupled to a rod of the air cylinder 29fixed to the base 21. The slide plates 23 are driven by the air cylinder29 in the horizontal direction.

The slide plates 23 support heat insulating plates 25 and 26 via pins23a such that the heat insulating plates can move up and down. The heatinsulating plates 25 and 26 are biased upward by springs 24, and made ofheat insulating material such as asbestos or ceramics on which theheater block 27 or cooling block 28 is fixedly mounted.

The heater block 27 is embedded with a temperature sensor and a nichromewire so that it is heated to a predetermined temperature.

The cooling block 28 is formed with an air communication hole 28s at thecenter thereof, and with a void 28b having an air inlet/outlet.

As shown in FIGS. 7(B) and (C), the air communication hole 28a isexposed within a cross groove formed in the upper end portion of thecooling block.

When the heater block 27 and cooling block 28 are raised by the aircylinder 20, they are pressed to the back of a lower die 30 to heat andcool the die. As shown in FIG. 7(D), the lower die 30 is also cooled byair flowing through the cross groove of the cooling block 28.

As shown in FIG. 6, the lower die 30 and upper die 31 are fixed to lowerand upper die setting plates 32 and 33, respectively.

The upper die setting plate 33 is slidably supported by a die settingpole 34 mounted upright on the lower die setting plate 32. The upper diesetting plate 33 is moved up and down by a rod 35 mounted upright on thebase 19. Specifically, as shown in FIG. 9, a hook 33b mounted on theupper die setting plate 33 engages with a pin 35a fixed to the end ofthe red 35.

As shown in FIG. 8(A) and (B), the upper and lower die setting plates 33and 32 are formed at the center thereof with holes 33a and 32a throughwhich the heater block and cooling block go in and out. The upper diesare set covering the holes.

A pair of the upper and lower die setting plates mounting the metal diesis squeezed at a die mounting base 45 as shown in FIG. 6. The diemounting base 45 is also formed with a hole 45a through which the heaterblock and cooling block go in and out.

As shown in FIG. 6, upper and lower pressure rings 36 and 37 for holdinga film are supported in a floating state by the upper and lower diesetting plates 33 and 32.

Specifically, shafts 39 are mounted upright on the pressure rings 36 and37. The shafts 39 are fitted in the holes of the die setting plates 33and 32. The pressure rings 36 and 37 are biased by springs 40.

Stoppers 41 for regulating a stroke of the pressure ring 37 are mountedon the lower die setting plate 32.

A sheet heater 38 with a temperature sensor is fixedly attached to theupper pressure ring 36.

As shown in FIG. 10, the lower and upper metal dies 30 and 31 are formedwith respective holes 30a and 31a extending from the pressing surfacesto the back surfaces.

One or two holes are generally formed in a metal die to allow air toescape in a closed space defined by a pair of upper and lower metaldies. In this embodiment, eight holes are formed to escape vaporgenerated when a film is heated.

FIG. 11 shows a modification of dies wherein holes extend toward theridge of dies so that vapor can escape more easily.

In this embodiment, two punching sections are provided to form a hole ina molded film or punching out an unnecessary portion.

The robot is an orthogonal type robot movable 1500 mm on the X axis and450 mm on the Y axis for transporting a film between the material supplysection, mold press, and punching section.

The film pickup arm and molded product pickup arm are mounted spaced by90 degrees. The arms are integrally moved up and down by a lift, and arerotated by 90 degrees by a rotary actuator. At each end of the armsthere is mounted a suction pad for sucking film.

An example of a film molded by the film molding apparatus constructed asabove will be described.

As the molding material, PPTA films having a thickness of 250 and awidth of 75 mm were wound in two rows about a bobbin to obtain a roll offilms.

This film roll was maintained so as not to become dry, and immersed inthe water vessel 1. The ends of the films were pulled out from the watervessel and set to the material supply section. Thereafter, the upperheater block of the mold press was set to 430° C. to 450° C., and thelower heater block to 510° C. to 550° C.

When the above-described temperatures were set, the film moldingapparatus was subject to a run-in for about 30 minutes without supplyingfilms so as to stabilize the temperatures of metal dies. Thereafter, thefilm molding apparatus was caused to enter an automatic operation.

Films were fed by 75 mm, and cut into film pieces. One cutting operationprovides two square film pieces having a thickness of 250μ and a slidelength of 75 mm, the film pieces being sent to the film receptor.

Each film piece is picked up by the robot film pickup arm, andtransported onto the pressure ring 37 under the condition that the metaldies are separated.

At this time, the temperatures of the metal dies were about 130° C. to140° C.

Next, the air cylinder 15 for raising/lowering the die starts lowering.During this period, the robot supplies film pieces to the other fourmold presses.

The gel film piece on the pressure ring is likely to emit water contentsand deform because of radiated heat from the heater block, dies and thelike. It is therefore preferable that the pressure ring is positioned asfar as possible from the dies, and that the die lowering speed is asfast as possible until the film piece is squeezed by the pressure ring.

However, a molding speed suitable for the gel film piece is used for amolding operation. In the case of the gel PPTA film used in thisembodiment, the lower the molding speed, the deeper the drawing waspossible under the room temperature condition.

Accordingly, it is preferable to control the cylinder speed by twosteps. In this embodiment, the cylinder lowering speed before the filmpiece is squeezed by the pressure ring was set to 150 to 200 mm/sec by aspeed controller mounted at the air inlet/outlet. The speed afterclamping the film piece, i.e., the molding speed, was set to 0.8 to 1mm/sec by an air exhaust needle valve in the air cushion chamber.

The pressure applied to the metal dies was set to 12 to 13 kg/cm².

While the metal dies press the film piece or before that time, the aircylinders 20 for raising/lowering the upper and lower blocks operate tolower the upper heater block 27 and raise the lower heater block 27, sothat they tightly press the upper and lower metal dies which are thenheated.

When the temperature of the male or upper metal die reaches 330° C. to350° C. and that of the female or lower metal die reaches 360° C. to380° C., the air cylinders 20 for raising/lowering the upper and lowerblocks operate to move the heater blocks 27 away from the metal dies.

When the heater blocks 27 return to the initial positions, the aircylinders 29 operate to slide the cooling blocks 28 at the positionscorresponding to the metal dies, and slide the heater blocks outside ofthe die setting plates.

Next, the air cylinders 20 for raising/lowering the upper and lowerblocks operate to lower the upper cooling block 28 and raise the lowercooling block 28, so that they tightly press the upper and lower metaldies. Air is then ejected out from the air outlet to cool the metaldies.

The metal dies are cooled to such a temperature not allowing adeformation of the film piece when it is detached from the metal dies.Then, the metal die raising air cylinder 15 rises to separate beth thedies. At the same time, the cooling blocks are separated from the diesand return to the initial positions.

In this embodiment, before the film piece is detached from the metaldies, the male metal die is cooled down to 140° C. to 150° C. and thefemale metal die is cooled down to 150° C. to 160° C.

A gel PPTA film piece is molded by the above processes. It is preferableto set the heating temperature to 330° C. or higher, or more preferably350° to 380° C., so as to obtain a molded product having stablemechanical characteristics and dimension.

In order to shorten a molding cycle, it is advantageous if thetemperatures of the metal dies before pressing are set as high aspossible. However, if the temperature is set to 200° C. or higher, watercontents evaporate near from the film surface immediately when the metaldies become in contact with the film piece. Therefore, the moldedproduct has a solid portion only near the surface and void vapor withinthe product, resulting in a poor product quality. In view of this, inthis embodiment the temperatures of the metal dies before pressing ispreferably set to 190° C. or lower. The temperatures depend on thethickness of the gel PPTA film. For example, the temperatures may be setabout 220° C. for a film thickness of 75μ. The molded film piece istransported to the punching section by the robot. One punching presspunches out holes, and the other punching press cuts out unnecessaryportions of the product.

The configuration of a speaker diaphragm molded according to theembodiment is shown in FIG. 12.

In FIG. 12, the diameter of the outer periphery of the flange is 35 mm,and the height of the flange is 1.5 mm.

The cylindrical section is formed inside the flange, this section has adiameter of 25 mm and a height of 3 mm. A dome about 4 mm is formed onthe top of the cylindrical section. Six holes of 6 mm diameter areformed in the flange at equal radial intervals to adjust the compliance.The flange is used as a suspension, the cylindrical section is used as acoil bobbin, and the dome is used as a sound radiating source. Thisspeaker diaphragm is constructed of an integrated combination of asuspension, coil bobbin, and diaphragm, having a reduced number ofmanufacturing processes, and a high Young's modulus allowingreproduction up to a high frequency range.

As described so far, according to the present invention, it is possibleto mold a PPTA film at deep drawing which has been heretoforeimpossible. By applying the present invention to a speaker diaphragm, itbecomes possible to obtain a speaker diaphragm integrally formed withdiaphragm, coil bobbin, and suspension. Since a PPTA film has a highelastic modulus and no adhesive agent is used, it is possible to obtaina diaphragm of small mass and high rigidity, thereby providing highfrequency reproduction. Furthermore, since the film has a high heatresistance, a high input power diaphragm can be obtained. For themolding operation, a roll film is not supplied to a mold press, but afilm piece corresponding to one molding product is supplied.Accordingly, heat to be applied to a film piece from the mold press canbe restrained minimum so that it is possible to prevent swelling agentfrom escaping from the film piece, and hence deformation of the film canbe prevented. A stable quality and high yield of products can thus beensured. Furthermore, it is possible to precisely determine positionswhere a punching process is executed later. The metal dies are heated byheater blocks and cooled by cooling blocks, so that a heating andcooling time is made short and the temperature can be controlledprecisely. The pressure ring is mounted on the die setting plate in afloating state, and the temperature of the pressure ring is madecontrollable. Accordingly, the clamping time of the molded film can bemade longer after the metal dies are separated, and the evaporation ofwater contents on the molded film at the clamped portion can be madeuniform, resulting in a uniform shape of the molded product. More holesare formed in the metal dies than conventional so that water contentscan be easily escaped from the film piece, resulting in a stably moldedproduct.

The film molding apparatus and method of the present invention isapplicable not only to a PPTA film containing water as swelling agent,but also to other films such as a polyimide film containing swellingagent. It can be easily understood that the present invention iseffectively applied also to other films susceptible to thermaldeformation, particularly in the form of roll film, such as films madeof or containing thermo-setting resin including epoxy resin, bismaleideresin and the like.

What is claimed is:
 1. A film molding apparatus comprising a film supplyvessel filled with soaking liquid for keeping a working film immersedtherein in a swelling condition so that the working film contains atleast 50 weight % swelling agent relative to a polymer constituting saidfilm;a mold press unit for mold-pressing the working film supplied fromsaid vessel; a passage for forwarding the working film supplied fromsaid film supply vessel to the mold press unit; a cover being arrangedto shield said passage; and a humidifier for supplying a vapor in aspace environment within said cover to prevent the working film in aswelled condition from being dried.
 2. A film molding apparatusaccording to claim 1, wherein said working film immersed in said filmsupply vessel is rolled on a bobbin, further comprising a cutter forcutting the working film rolled out from said bobbin into a working filmpiece.
 3. A film molding apparatus according to claim 1, furthercomprising means for wiping out the soaking liquid on the surface of theworking film taken out from said film supply vessel.
 4. A film moldingapparatus comprising:a film supply vessel filled with soaking liquid forkeeping a working film immersed therein in a swelling condition so thatthe film contains at least 50 weight % swelling agent relative to apolymer constituting the film; metal dies for press-molding a workingfilm piece supplied from said vessel and in the swelling condition;heating and cooling blocks thermoconductively separated from said metaldies in their normal positions; a first drive unit for moving saidheating block into thermoconductive contact with the back of said metaldies while said metal dies are press-molding the working film piece todry and crystalize the working film piece, said heating block beingpreviously heated before being moved; and a second drive unit for movingsaid cooling block into thermoconductive contact with the back of saidmetal dies while said metal dies are press-molding the working filmpiece but after said heating block has been left from said metal dies,said cooling block being previously cooled before being moved.
 5. A filmmolding apparatus comprising metal dies, a heater block and a coolingblock, said heater block and cooling block being mounted on respectivemounting plates and movable by driver units to tightly contact with theback of said metal dies for heating and cooling said metal dies, saidapparatus further comprising:a floating member located between themounting plates and the driver unit for holding the mounting plates in afloating state relative to the driver units.
 6. A film molding apparatusaccording to claim 5, further comprising upper and lower rings forholding a working film to be set between said metal dies, wherein aheater is provided to one or both of said tings to heat the one or bothof said rings to a predetermined temperature.
 7. A film moldingapparatus for press-molding a working film piece containing swellingagent, the apparatus comprising:upper and lower metal dies forpress-molding the working film piece; drive means for driving said metaldies so that an approaching speed of said metal dies in a pressingoperation is slowed down when said metal dies become in contact with theworking film piece; and heating means for heating said metal dies tomaintain said metal dies below a predetermined temperature until saidmetal dies are in contact with the working film piece and then raise thetemperature of said metal dies over said predetermined temperature.
 8. Afilm molding apparatus according to claim 4, wherein said cooling blockcomprises a metal body through which a cooling medium flowing passage isprovided.
 9. A film molding apparatus according to claim 5, wherein saidcooling block comprises a metal body through which a cooling mediumflowing passage is provided.